1. Field of the Invention
The present invention relates to a method for manufacturing a lithium cobaltate oriented sintered plate.
2. Description of the Related Art
Positive electrode active materials including a lithium complex oxide (lithium transition metal oxide) having a layered rock-salt structure are widely known as positive electrode active materials in lithium secondary batteries (which may be referred to as lithium ion secondary batteries). It is known that, in positive electrode active materials of this type, lithium ions (Li+) therein diffuse along an in-plane direction of the (003) plane (i.e., any direction in the plane parallel to the (003) plane), while intercalation and deintercalation of lithium ions occur through a crystal plane other than the (003) plane (e.g., the (101) plane or the (104) plane).
Accordingly, in positive electrode active materials of this type, attempts have been made to enhance battery characteristics of lithium secondary batteries by exposing a crystal plane through which lithium ions are favorably intercalated and deintercalated (i.e., a plane other than the (003) plane, such as the (101) plane or the (104) plane) to a surface which comes into contact with a larger amount of electrolyte. For example, Patent Document 1 (WO2010/074304) discloses the production of a LiCoO2 oriented ceramic sheet (a positive electrode active material film) having the (104) plane parallel to the sheet surface, by firing a Co3O4-containing green sheet to form a sheet containing Co3O4 grains oriented such that the (h00) plane is directed in parallel with the sheet surface, and then introducing lithium. Moreover, this document further discloses the addition of Bi2O3 as a grain growth promoter to the Co3O4-containing green sheet.